1. Field of the Invention
This invention relates to laundry machines, and more particularly to a belt drive mechanism used in automatic clothes washers.
2. Description of the Prior Art
Automatic clothes washing machines have at least two modes of operation, a washing mode and a spin mode. During the washing mode the vertical center post vaned structure or agitator is oscillated by means of a motor driven belt drive mechanism through a transmission. At the start of the washing mode there is a considerable load on the motor because the clothes washing machine is full of the clothes to be washed and wash water. Considerable weight needs to be initially rotationally moved during startup of the motor and it is desirable to reduce the torque requirements on the motor at that time. In the spin mode there also needs to be provided a means to reduce the torque required of the motor in order to prevent overloading thereof without requiring a larger and more expensive motor. It is, therefore, desirable to provide some means of relieving the belt tension and thereby reducing the torque required of the motor during the initial stages of the washing mode and the spin mode. This is particularly true when there are occurrences of abnormally low voltage being available to the motor which reduces its torque capabilities during startup.
After the wash mode is completed the clothes washing machine is programmed by its controls to pump the wash liquid out of the tub to an external drain. This may be done by spinning the basket containing the clothes and having the liquid being pumped out of the machine during the spin operation. It is desirable, however, to provide for removal of the liquid by the motor driven pump without the motor also being required to operate some other function of the machine such as agitating the vaned structure or spinning the basket containing the clothes. Such a system enhances subsequent liquid extraction from the clothes during the spin mode.
Belt drive systems in laundry machines wherein belt tension is relieved during certain operational modes of the machine have been employed. One example is shown in U.S. Pat. No. 3,525,241 wherein a solenoid actuated mechanism relieves an idler pulley from tensioning the belt thus allowing belt slippage in only the spin mode of operation. Another prior art arrangement is shown in U.S. Pat. No. 3,324,691 wherein a solenoid is operable to disengage an idler pulley from a drive belt and effect a slipping belt drive during high speeds to limit torque input to the washer basket during the spin operation.
By my invention I have improved the prior art belt drive mechanisms to provide a means for assuring that the belt will slip during startup of the motor in both the wash and spin modes of operation and it also provides, if desired, for not operating either the agitator or the rotation of the basket during operation of the pump to remove liquid from the machine prior to the spin mode.